James gresham



(No Model.)

Patented-Mar. 20, 1894.

Jam/ante)":

wvbn/asses @zwal UNITED ST TES PATENT OFFICE.

JAMES eREsnAM, or MANCHESTER, ASSIGNOR TO THE VACUUMBRAKE COMPANY,LIMITED, or LONDON, ENGLAND.

VACUUMAUTOMATIC BRAKE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 516,863, dated March20, 1894.

Application filed May 23, 1892; Serial No- 4=33,9.59. (No model.)

To aZZ whom it may conceive.-

Be it known that I, JAMES GRESHAM, engineer, a subject of the Queen ofGreat Britain and Ireland, of the firm of Gresham & Graven, Limited, ofCraven Iron Works, Salford, Manchester, in the county of Lancaster,England, have invented new and useful Improvements in or Applicable toVacuum AutomaticBrake Apparatus, (in respect whereof I have applied forbut not yet obtained Letters Patent in Great Britain, No.-22,0l9, tobear date December 16, 1891,) of which the following is a specification.

This invention relates to the construction of the ball-valve gear forcontrolling vacuum brake apparatus, the same being arranged in such amanner that, when taken apart, the ball cannot be lost or damaged, and,when put together again, the parts cannot be improperly assembled inconsequence of inadvertency or want of knowledge on the part of theworkman. I I g In ordinary ball-valve apparatus, the ball is droppedthrough anormally-closed aperture in the casing into a hole or cavity inthe movable stem by which the ball is pulled off its seating; the stempassing through a diaphragm employed for enabling the pressure oftheatmosphere to restore the parts to their original positions. 7

According to the present improved mode of construction, the ball iscarried and retained in the hole or cavity in the movable stem; the holeor cavity being large enough to allow perfect freedom of action when theball is being lifted from or is falling back to its seating. The slot orchannel on the lower side of the stem is of less width than the diameterof the ball. The ball, however, acts freely, as its seating projectsinto the aperture. Inasmuch as the ball can only pass partly through theaperture; and is retained on the side opposite to the aperture by aremovable cross-pin, it cannot fall out of the hole or cavity when thestem is withdrawn from the casing. That part of the stem containing thehole or cavity for the ball is on one side of the axis of the stem,which provents the stem from being inserted in the guiding hole in thecasing except when it is the proper side up. This also insures that thelever for actuating the stem when the ball is to be moved out of itsworking position, which lever is pivoted to the stem, shall be in itscorrect place.

In the accompanying drawings, Figure l is a vertical section, on theline B B (Fig. 2), of the improved ball-valve mechanism. Fig. 1 shows anaddition sometimes employed in hot climates. Fig. 2 is a correspondinghorizontal section on the line A A (Fig. 1). Fig. 3 is a verticalsection, on the line C C (Fig. 1),

looking toward the left.

The casingaof theball-valve mechanism has a flange a by means of whichit is united to the brake-cylinder, the passage a communicating with theunder side and the passage a with the upper side of the piston in thevacuum-chamber. The nozzle a of the casing a'is adapted to receive oneend of the flexible tube which connects it with'the train-pipe,thelatter extending from end to end of the train. is a branch from thepassage of the nozzle 01. on each side of the passage a these branchescommunicating with the passage a above the ball-valve. When air iswithdrawn from the train-pipe, air from the upper side of thebrake-piston flows through the passage a and,

by the ball-valve c to the passage a thence to the passage or and,through the flexible tube, to the train-pipe. side of the piston canalso flow at the same time along the passages a and a and through thetube to the train-pipe, Thus the brakecylinde'r on both sides of thepiston is exhausted more or less, and the piston can descend to itslowest position, in which position the brake-blocks are withdrawn fromthe wheels.

When air is admitted from the atmosphere to the train-pipe, it flowsthrough the flexible tube and passages a and a to the under side of thepiston, but itcannot enter the vacuumchamber which incloses the upperend of the brake-cylinder; the vacuum on the upper side of the pistonbeing therefore maintained, because the ball-valve c is kept closed bythe pressure of the incoming air, and communi- There Air from the undercation through the passage 0, is intercepted. The pressure of theatmosphere, acting on the lower side of the piston, lifts the same,thereby applying the brake-blocks. The ball-valve o is retained in thehole or cavity in the movable stem 0 by the cross-pin 0 The seating forthe ball is formed in the casing a, and projects upward into a slot orchannel on the under side of the hole in the stem; the slot or channelnot being wide enough to allow the balloto escape when the stem iswithdrawn from the casing.

The central part of the flexible diaphragm cl is held between a collar 0on the stem and a nut c screwed on the end of the stem; the margin ofthe diaphragm being secured between facings formed upon the casing a andthe part e, which is attached to flanges on the casing a by bolts andnuts. The outer eX- tremity of the stem 0 is jointed to a lever 0extending across the dished end of the part e, so that the lever 0 whenpulled either way, acts against the edge of the dished end, whichservesasafulorum. Whenthestemc'isdrawn outward by moving the lever 0 theside of the hole or cavity in the stem is brought against the ball 0 andpushes it ofif its seating; thereby admitting air from the train-pipe tothe brakecylinder above the piston. The lever 0 may be manipulated by acord attached to it at the hole in its extremity. This lever is notrequired in the ordinary working of the brakes, but is furnished inorder that, after the enginehas been detached from the train and airhas, in consequence, been admitted to the brake-cylinder, thus puttingthe brakes on, air can also be admitted to the vacuum chamber, thusre-establishing equilibrium and taking the brakes off. The annular spacebetween the part c and the stem 0 effects COlllmunication between theouter side of the diaphragm cl and the atmosphere, so that atmosphericpressure can force the diaphragm d inward, when there is a more or lessperfeet vacuum in the passage a and bring the stem into the positionshown in Figs 1 and 2, in which position the hole in the stem isconcentric with the ball-valve c.

The screw plug f is used for closing a hole which gives access to thepassage a this hole also serving to enable the core of the passage a tobe supported in the mold during the operation of casting.

It, while air is being exhausted from the train-pipe b, the valve Zallows air, entering by way of the valve n, to leak pastit into thetrain-pipe to such an extent as to interfere with the ejector creatingsuflicient vacuum, the lever a should be turned so as to draw down thevalve n. air-tight against its seating; leakage past the valve Z, beingthus prevented.

When the ball-valve mechanism is required for use in hot climates, wherethe heat is sufficient to harden the diaphragm d, it is desirable toplace between the stem 0', and the dished end of the part 6, afriction-spring 0, which serves to retain the ball valve either in theopen or in the closed position.

Having now particularly described and ascertained the nature of thisinvention and in what manner the same is to be performed,I claiinv V Inball-valve apparatus for controlling vacuum automatic brakes, thecombination, with a ball-valve c, a movable stem 0, for unseating thatvalve, a cavity in the stem wherein the said valve works, a pin 0 acrossthe cavity above the ball, and a slot in the bottom of the cavity havingsides which serve to support the ball when the stem is withdrawn fromits guiding hole, of the casing a containing the guiding hole for thestem 0', and

a seating for the ball-valve c projecting upward from the casing intothe slot on the under side of the cavity in the stem, substantially asherein set forth.

JAMES GRESHAM.

\Vitnesses:

G. E. BECKETT, H. E. GRESHAM.

